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EEE :: Inductors

  1. The winding resistance of a coil can be increased by

  2. A.
    increasing the number of turns
    B.
    using a thinner wire
    C.
    changing the core material
    D.
    increasing the number of turns or using thinner wire

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  3. An inductance of 0.43 mH is smaller than

  4. A.
    43 H
    B.
    430 H
    C.
    0.05 H
    D.
    0.00043 H

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  5. An inductor and a resistor are in series with a sine wave voltage source. The frequency is set so that the inductive reactance is equal to the resistance. If the frequency is increased, then

  6. A.
    VRVL
    B.
    VL < VR
    C.
    VL = VR
    D.
    VL > VR

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  7. The current through a 120 mH coil is changing at a rate of 150 mA/s. The voltage induced across the coil is

  8. A.
    1.8 mV
    B.
    18 mV
    C.
    180 mV
    D.
    1.25 mV

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  9. When the current through an inductor decreases, the amount of energy stored in the electromagnetic field

  10. A.
    increases
    B.
    decreases
    C.
    remains the same
    D.
    doubles

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  11. Three 15 mH inductors are in series. The total inductance is

  12. A.
    15 mH
    B.
    30 mH
    C.
    45 mH
    D.
    5 mH

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  13. An 18 V power supply is connected across a coil with a winding resistance of 180 . Current flow in the coil is

  14. A.
    1 mA
    B.
    10 mA
    C.
    100 mA
    D.
    1 A

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  15. A switch, a 220 resistor, and a 60 mH inductor are in series across a 20 V battery. What is the current through the inductor two time constants after the switch is closed?

  16. A.
    91 mA
    B.
    78 mA
    C.
    57 mA
    D.
    400 mA

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  17. A 320 H coil is in series with a 3.3 k resistor. How long does it take for current to build up to its full value?

  18. A.
    0.48 s
    B.
    0.48 ms
    C.
    0.48 s
    D.
    48 s

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  19. Five inductors are connected in series. The lowest value is 8 μH. If the value of each inductor is twice that of the preceding one, and if the inductors are connected in order of ascending values, the total inductance is

  20. A.
    8 H
    B.
    32 μH
    C.
    64 μH
    D.
    248 μH

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